Clutch is running me in circles

[whittenetx]

91 k1500 5spd my clutch pedal never really worked 100% but I would say atleast 8.5/10 but about a couple weeks ago it would randomly go to the floor. Didn't feel like guessing & parts are cheap so I just replaced the slave and master at the same time and bled it until it felt better than it ever has. Drove home didn't make it half way to town and it was doing it again so I bled it again when I got home with the same results. It will work perfectly when I'm bleeding it than randomly while driving no pedal at all. And then I might get a mile down the road and it works half way again... I know sometimes getting all the air out can be tricky but I've bled this this atleast 10+ occurrences over a couple weeks with no permanent improvement. And another detail I have no leaks external slave cylinder only one line from it to the master cylinder so it would be easy to see also fluid stays full.... needless to say I'm stumped please help

 

[RacerM95]

check the pivot ball and the pivot fork.. had the same issue on a 94 with NV4500.

 

[whittenetx]

check the pivot ball and the pivot fork.. had the same issue on a 94 with NV4500.

Would that be internal?

 

[RacerM95]

Yes

 

[Erik the Awful]

Inside the bellhousing, but not inside the transmission case. If your clutch fork is falling off the pivot, or if the pivot has worn through the fork you'll get the symptoms you're seeing.

 

[movietvet]

Besides the recommended info from @Erik the Awful and @RacerM95, make sure to check and see if the firewall area, where the clutch master is mounted, is not flexing. Also, make sure the clutch pedal pivot mount area and attachments are in good working order. By the way, how did you bleed it. I used to have and will get again, a power bleeder, that uses air to force the fluid into the system.

 

[RacerM95]

good point @movietvet .. Havent seen the firewall be an issue, have seen worn out pedal pivot bushings though,and/or worn pivot bolt ..... The Porsche 944 is pretty bad for a flexing firewall, i have an 1/8th inch flex plate that covers my brake booster and master and clutch master

 

[movietvet]

good point @movietvet .. Havent seen the firewall be an issue, have seen worn out pedal pivot bushings though,and/or worn pivot bolt ..... The Porsche 944 is pretty bad for a flexing firewall, i have an 1/8th inch flex plate that covers my brake booster and master and clutch master

Yea, just throwing spit balls and seeing what sticks.

 

[thinger2]

Yep. worn bushings do not allow enough pedal throw to completely bleed the system.
It is a mechanical loss of travel.
Works great at first because all of the air in the system has sat long enough to become "big bubbles" and it will bleed because the bigger volumn of air has enough force to blow out of the bleed screw and make it look like you have gotten all of the air out.
When you push the pedal again that air in the system turns into a bunch of "small bubbles"
It basically froths and all of those small micro bubbles get trapped in every little corner .
And after some time they reform as big bubbles and rinse and repeat.
If you really want to loose your mind try this on a 90s Ford with the aluminum pedal bracket and the .020 plastic bushings.
The holes oval out so bad that the clutch wont disengage anymore because most of your foot is just pushing the comman pedal shaft into the ovalled out hole and dosent transfer into moving the clutch.